1. Field of the Invention
The present invention relates to an ECC (Error Check and Correct) control apparatus for use in storing data output from a host into a memory and reading data from the memory to the host. More particularly, it relates to an ECC control apparatus of the type that is provided on a bus connecting a host and a memory.
2. Description of the Related Art
The number of levels of data, which one memory cell can store, may be changed from two to three or more (multi-level). Then, memory cards using memory cells used as storage elements can have their data storage capacity increased. In a memory card having memory cells that store multi-level data, the memory cells deteriorate as they keep holding the data for a long time or as data is repeatedly written to and read from them. As a consequence, the data stored in the memory card more decreases in terms of reliability than the data stored in memory cards that store binary data.
Memories with a new error-correcting means have been proposed, in which the memory cells are prevented from deteriorating. (Such a memory is disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication 2000-349652.)
To incorporate an error-correcting means into the memory provided in a memory card, however, it is necessary to re-design the circuits used in the memory card or in the host that writes data into the memory card. If the circuits in the host are changed in design, the host will need to process more data to control the error-correcting means.